Rental boilers here means temporary boiler plant hired by the month while a building's own boiler is down, being replaced, or cannot yet carry a winter load. Small electric skid units start near $1,000 a month; trailer-mounted fired boilers in the megawatt class run into five figures. It is specialist plant hire, so the general rental counter that stocks heaters will not have one.
Sized in horsepower or BTU, not in gallons
Temporary boilers are quoted by boiler horsepower or by input BTU per hour, and the number you need comes from the load you are replacing rather than from the building's floor area. The mechanical contractor or the existing boiler's nameplate gives it. Renting a unit a size up is common, since a cold building recovering from zero draws more than it does in steady state.
What the monthly rate does not include
The rate is for the boiler on site. Fuel is yours, whether that is gas, oil or electricity, and on a fired unit it usually costs more than the rental. Hook-up hoses, manifolds, a temporary electrical supply, water treatment and the pump set are separately priced. Mobilisation and demobilisation are one-off charges at each end of the hire.
The permissions that decide the start date
A trailer-mounted fired boiler on a public-facing site typically needs a placement location agreed, a fuel supply arranged and, in many jurisdictions, a local mechanical or fire permit before it fires. Those lead times, not the yard's availability, are what usually sets when heat arrives. Ask the supplier which of them they handle and which fall to you.
When a heater is the right rental instead
If the requirement is construction heat, drying out a slab or keeping a trade working through a cold week, direct or indirect fired heaters hired by the day from a machinery yard are far cheaper and need no water side at all. A rental boiler earns its cost only when an existing hydronic or steam system has to keep running.
Questions people ask about rental boilers
How quickly can a rental boiler be on site?
Suppliers hold trailer-mounted units regionally and can often deliver within a day or two. Firing it is the slower half: fuel supply, a permit where one is required and the hook-up crew normally take longer than the delivery does.
Are rental boilers priced by the day?
Very rarely. Temporary boiler plant is quoted monthly or for a defined project term, because mobilisation, hook-up and demobilisation dominate the cost of a short hire.
Electric or fired?
Electric skids are quiet, need no flue and suit indoor plant-room replacement where the supply exists. Fired units carry far more output per trailer and suit winter loads, but they need fuel, clearance and combustion air.